车道偏离警示系统

车道偏离警示系统（英文：Lane Departure Warning System，LDWS），是一项汽车驾驶安全辅助系统。

当传感元件侦测到车辆偏离车道时，若驾驶者因精神不济或疏忽而未打下转换车道的方向灯讯号，系统会发出警示讯号以提醒驾驶者返回车道。

历史首次装设车道偏离警示系统是在Nissan Motors 的Infiniti FX 系列和Infiniti M系列，该系列的系统是由Valeo 和Iteris 两车商联合开发，系统的影像传感器是装置在车内照后镜的位置。

2000年，在欧洲是由Iteris 车商为Mercedes Actros 商务车开发使用车道偏离警示系统，现今在全欧洲多数的大型商用车都装有此系统。

后来在2002年，北美的Freightliner卡车才拥有此系统装设。

2007年，日本Mitsubishi Fuso 也随之跟进运用这项系统。

雪铁龙2005年，雪铁龙Citro?n 4 和Citro?n 5 都装设车道偏离警示系统，现今Citro?n 6 也已加装这项系统，Citro?n 的系统是运用装设在前方保险杆上红外线传感器监测路面上车道标志，发生车辆偏离车道时，以振动座椅的方式提醒驾驶返回车道。

Infiniti2008年，Infiniti车系将装设预防车道偏离系统（Lane Departure Prevention，LDP），这系统是运用车身稳定控制系统（ESP）的煞车力控制，协助驾驶将车辆维持在车道内，车道偏离警示系统协同车身稳定控制系统作动时，是以轻柔的煞车力控制，不让驾驶与乘客在乘车感到不适为原则。

Lexus 车商使用多重传感车道保持辅助系统（Multimode Lane Keeping Assist），这系统特点在于使用复数的3D影像传感器，并配合红外线传感器，在物体和影像的多重传感及MCU 运算下，监控车辆保持在车道内。

Lexus LS更提供了视觉警示和控制转向系统使车辆回到车道内。

GM车商在2007年发表在2008年的Cadillac STS, DTS 和Buick Lucerne上装备车道偏离警示系统，这系统与Infiniti的系统有相同之处在于用视觉和听觉的警示。

BMW车商在2007在5系列和6系列是使用振动方向盘方式，警示驾驶的车辆偏离车道。

Volvo车商在2008年的S80和New V70和XC70系列，则是配以影像传感器来传感车道标志的车道偏离警示系统。

TypesThere are two main types of systems:
systems which warn the driver (lane departure warning, LDW) if the vehicle is leaving its lane. (visual, audible, and/or vibration warnings)
systems which warn the driver and if no action is taken automatically take steps to ensure the vehicle stays in its lane (lane keeping system, LKS).
The first production lane departure warning system in Europe was developed by the United States's Iteris company for Mercedes Actros commercial trucks. The system debuted in 2000 and
is now available on most trucks sold in Europe.
In 2002, the Iteris system became available on Freightliner Trucks' trucks in North America. In all of these systems, the driver is warned of unintentional lane departures by an audible rumble strip sound generated on the side of the vehicle drifting out of the lane. No warnings are generated if, before crossing the lane, an active turn signal is given by the driver.
Sensor types Lane warning/keeping systems are based on:
Video sensors in visual domain (mounted behind the windshield, typically integrated beside the rear mirror)
Laser sensors mounted in the vehicle front
Infrared sensors (mounted either behind the windshield or under the vehicle)
Audi began in 2007 offering its Audi Lane Assist feature
Timeline of available systems2001: Nissan Motors began offering a Lane Keeping Support system on the Cima sold in Japan. In 2004, the first passenger vehicle system available in North America was jointly developed by Iteris and Valeo for Nissan on the Infiniti FX and in 2005 the M vehicles. In this system, a camera mounted in the overhead console above the mirror monitors the lane markings on a roadway.A warning tone is triggered when the vehicle begins to drift over the marking to alert the driver. In 2007 Infiniti offered a newer version of this feature, which it calls the Lane Departure Prevention (LDP) system.This feature utilizes the vehicle stability control system to help assist the driver maintain lane position by applying gentle brake pressure to the appropriate wheels.
2002: Toyota introduced its Lane Monitoring System on vehicles such as the Cardina and Alphard sold in Japan, this system warns the driver if it appears the vehicle is beginning to drift out of its lane. In 2004, Toyota added a Lane Keeping Assist feature to the Crown Majesta which can apply a small-counter steering force to aid in keeping the vehicle in its lane. In 2006, Lexus introduced a multi-mode Lane Keeping Assist system on the LS 460 which utilizes stereo cameras along with more sophisticated object and pattern recognition processors, this system can issue an audiovisual warning and also using the Electric Power Steering (EPS) steer the vehicle to hold its lane, this system also applies counter-steering torque to help ensure the driver does not over-correct or "saw" the steering wheel while attempting to return the vehicle to its proper lane, if the radar cruise control system is engaged the Lane Keep function works to help reduce the driver's steering input burden by providing steering torque, however the driver must remain active otherwise the system will deactivate.
2003: Honda launched their Lane Keep Assist System (LKAS) on the Inspire.[13][14] It provides up to 80% of steering torque to keep the car in its lane on the highway. It is also designed to make highway driving less cumbersome by minimizing the driver's steering input.[15] A camera is mounted at the top of the windshield, just above the rear-view mirror scans the road ahead in a 40-degree radius, picking up the dotted white lines used to divide lane boundaries on the
highway. The computer recognizes that you're locked into a particular lane, monitors how sharp the curve is and uses factors such as yaw and vehicle speed to calculate what steering input is required.[16]
2005: Citro?n became first in Europe to offer LDWS on their 2005 C4 and C5 models, and now also on their C6. This system uses infrared sensors to monitor lane markings on the road surface.
A vibration mechanism in the seat alerts the driver of deviations.[17] Audi began in 2007 offering its Audi Lane Assist feature[18] for the first time on the Q7. This system unlike the Japanese "assist" systems will not intervene in the actual driving rather vibrate the steering wheel if the vehicle appears to be exiting its lane. The LDW System in Audi is based on a forward-looking video-camera in visible range as opposed to the downward-looking infrared sensors in Citro?n.[19]
2007: General Motors introduced Lane Departure Warning on its 2008 model year Cadillac STS, DTS and Buick Lucerne models. The General Motors system warns the driver, with an audible tone and a warning indicator in the dashboard. BMW also introduced Lane Departure Warning on the 5 series and 6 series using a vibrating steering wheel to warn the driver of unintended departures. Volvo introduced the Lane Departure Warning system along with the Driver Alert Control on its 2008 model year S80 and on the new V70 and XC70 executive cars. Volvo's lane departure warning system uses a camera to track road markings and sound an alarm when drivers depart their lane without signaling. The systems used by BMW, Volvo, and General Motors are based on core technology from Mobileye
2009: Mercedes-Benz began offering a Lane Keeping Assist function on the new E-class.[20] This system warns the driver with a vibrating steering wheel if it appears the vehicle is beginning to leave its lane. And a new feature will automatically deactivate and reactivate if it ascertains the driver is intentionally leaving his lane, for instance if the driver is aggressively cornering. A newer version will use the braking system to assist in maintaining the vehicle's lane.
2010: Kia Motors offers the 2011 Cadenza premium sedan with an optional Lane Departure Warning System (LDWS) in select markets. This system uses a flashing dashboard telltale and emits an audible warning when a white lane marking is being crossed, and emits a louder audible warning when a yellow line marking is crossed. This system is canceled when a turn signal is operating, or by pressing a deactivation switch on the dashboard. The system works by using an optical sensor on both sides of the car.
FIAT is also launching its Lane Keep Assist feature based on TRW's lane keeping assist system - also known as the Haptic Lane Feedback system. This system integrates the lane detection camera with TRW's Electric Power steering system - when an unintended lane departure is detected (the turn signal is not engaged to indicate the driver's desire to change lanes)the electric power steering system will introduce a gentle torque that will help guide the driver back toward the center of the lane. Introduced on the Lancia Delta in 2008, this system earned the Italian Automotive Technical Association Best Automotive Innovation of the Year Award for 2008.Peugeot introduced the same system than Citro?n in its new 308.
Lane departure warning systems are now combining prevention with risk reports in the transportation industry. Viewnyx applies video based technologies to assist fleets in lowering their driving liability costs. By providing Safety Managers with driver and fleet risk assessment reports and tools to facilitate proactive coaching & training to eliminate high risk behaviors. The Lookout solution is currently being used by North American fleets. There are first solutions for implementing a lane departure warning system on a mobile phone.[21]
[edit] Vehicles supporting adaptive cruise control。